Pereira has shone for the Baggies ever since initially arriving on loan from Sporting Lisbon in August last year.
But his outstanding performances – together with Albion’s relegation from the Premier League – have led to speculation he will leave the club this summer.
Earlier this week, Jolden Vergette, one of Pereira’s clients, was asked if his client would prefer to stay in the top flight.
“It will present itself,” he said.
“He deserved a club that can follow his work at a high level.”
Robertson, though, believes Albion should only sell Pereira if they receive an offer between £25million and £30million.
And even then he would only sell him if that money is reinvested into the team.
“If we are going to sell Pereira, we have to then go out and buy three or four players to make the squad better,” said Robertson who made more than 600 appearances for the club between 1969 and 1986.
“If we do that then I won’t have a problem.
“In an ideal world I’d like him to stay and for us to build a team around him.
“But if an offer in the region of £25million or £30million comes in then I can understand us accepting that if it’s to give the manager funds to strengthen.
“But we can’t just sell him and do nothing, that money has to be reinvested.
“And we have to sell him for that amount, selling him for £20million or £15million would be wrong.”
If Pereira does leave, Robertson admits he will be very interested to see where he ends up.
“He has been fantastic for us.” he added.
“I think there have been times when he’s been guilty of letting players run past him which may put off some clubs.
“But his performances for us over the last two years, at times, have been inspirational. He has got wonderful ability.”